Right, but I'm not sure how that resolves the issue. I mean, whether we call it color neutrality or color confinement, the end result seems to be that there are no colored eigenstates, so \langle n|\psi_a(0)|0\rangle would seem to vanish, along with the quark propagator. I don't think this can...
Hi everyone! Something has been bothering me lately. Consider the quark propagator:
\langle 0|\psi_a(x)\psi_a(0) |0\rangle
For a given color a. Now let's say we insert 1 = \sum |n \rangle \langle n| between the two quark fields, where the sum is over a complete set of energy...